The Preparation And Performance Research Of Silk Fibroin-? Collagen Cartilage Scaffold

Articular cartilage is a kind of viscoelastic connective tissue covering the surface of the joint.It has the effect of lubricating,absorbing shock and transferring load to the subchondral bone.Because of its lack of blood supply,innervation and lymphatic reflux,its self repair ability after injury is very limited.Although modern medicine has many new technologies and new methods to treat cartilage defects,the overall efficacy is generally not satisfactory.The proposal of tissue engineering provides a new idea for the repair of cartilage damage.In vitro tissue culture of tissue engineering scaffolds is an important part of cartilage tissue engineering.Therefore,designing and preparing tissue engineered scaffolds with good comprehensive properties is of great significance for its tissue culture.In this paper,natural silk fibroin and articular cartilage were used as raw materials to extract silk fibroin solution and type II collagen.After the two were mixed in a certain proportion,three-dimensional fibroin-? collagen was prepared by low temperature 3D printing and freeze-drying Porous scaffolds.First,the physical properties such as density,porosity and water absorption of the scaffolds were measured.Then,the stress relaxation,creep,and rate related experiment for mechanical properties of the scaffold were carried out.The results show that both the initial stress and instantaneous stress of scaffold increase with the increase of compressive strain during the stress relaxation process.Under the constant compressive strain,the stress of scaffold decreases rapidly first and then slowly decreases.Under different stress levels,the creep strain of scaffold showed the tendency of increasing slowly and then slowly increasing.As the stress level increased,the creep strain of the stent increased.When the creep load was removed,the scaffold subjected to less than 35 kPa stress Can be resumed in PBS buffer deformation,and withstand greater than 50 kPa stress scaffold structure is damaged,can not be restored.No matter under uniaxial compression or uniaxial tensile load,the elastic modulus and stress-strain curves of scaffolds all showed a rate-dependent relationship,that is,the fibroin-? collagen scaffold was a rate-dependent nonlinearity Viscoelastic material.Based on the constitutive equation of Drozdov and Lou and Schapery,the nonlinear and viscoelastic characteristics of scaffold were considered.In this paper,a relaxed constitutive model and a creep constitutive model were established.The stress relaxation behavior of the scaffolds under different compressive strains and the creep properties of the scaffolds under different stress levels were predicted,and compared with the experimental results.The results showed that the model predictions agreed well with the experimental results.The established relaxation model and creep model could well predict the stress relaxation behavior and creep behavior of scaffold.Bone marrow mesenchymal stem cells were extracted and cultured with Percoll density gradient centrifugation,and chondrocytes were induced by soft ossification.The effects of mechanical load on the proliferation and proliferation of chondrocytes in fibroin-? collagen scaffolds were observed by MTT assay,HE staining and scanning electron microscopy.The results showed that the silk fibroin-type? collagen scaffold had good biocompatibility.By comparing the growth and proliferation of cells under different loadings,it was found that the chondrocytes grew and proliferated fastest when the compressive strain reached 10%.The preliminary results showed that the silk fibroin-type? collagen scaffold prepared in this paper is a kind of tissue engineering scaffold with better comprehensive performance.